In Drive, Craig Manning invites Sean, Marco, and Spinner Mason to his house. They decide to prank call people and Marco dials a number and gives Sean the phone. The person on the phone is revealed to be Sean's ex-girlfriend Emma Nelson. Sean is shocked and chases Marco around the room.
In Careless Whisper, Sean makes fun of Marco for supposedly checking him out.
In Don't Dream It's Over, Ellie and Marco go to the movies where Jay looks at him weird; then he and Alex go buy popcorn. Sean is disappointed that Marco is there but just wants to get seats. Sean is at the movies and looks at Marco who is laughing at the movie. Sean goes to eat popcorn but Marco's hand is there and quickly pulls it away. At school, Sean sees Ellie sitting with Marco and tries to get Marco out of there so he and Ellie can talk; she gets mad and leaves. Later, Ellie tells Marco she's dumping Sean, but he says Sean can be great for her. She then finds Sean and tells him she's sorry, and they kiss.
In Anywhere I Lay My Head, Marco attends Sean's house party.
In Back In Black, Marco and Sean were seen at the school's respect and reflection day after the school shooting.
- Marco was four months older than Sean: Marco was born in June 1988 while Sean was born the following October.
- They both dated Ellie Nash. Ellie also had an unrequited crush on their mutual friend Craig Manning but her feelings for him were eventually returned.
- They were both friends with Spinner Mason and Manny Santos.
- Sean had a conflict with Marco's close friend Jimmy Brooks but it was eventually resolved.
- They both share the same line, "Go to hell."
- They were both the closing character for the opening credits:
- Both have worn braces.
- They were both big fans of Kid Elrick.
- They both had problems with one or both of their parents: Sean's parents Mr. Cameron and Nona Cameron were alcoholics, which led him to live with his elder brother Tracker Cameron, while Marco's father Mr. Del Rossi's homophobia made Marco reluctant to come out to him for several years, though he eventually came to accept it.
- They both prevented a friend from committing suicide: Sean saved Craig in When Doves Cry (2) while Marco (and Craig) saved Ellie in Degrassi Goes Hollywood.
- They were both originally members of the Class of 2006. While Marco graduated in High Fidelity (2), Sean was held back in Eye of the Beholder and expelled in Here Comes Your Man (2).